While the normal immune system is closely regulated, aberrations in immune responses are not uncommon. In some instances, the immune system functions inappropriately and reacts to a component of the host as if it were, in fact, foreign. Such a response results in an autoimmune disease, in which the host's immune system attacks the host's own tissue. T cells, as the primary regulators of the immune system, directly or indirectly effect such autoimmune pathologies. T cell-mediated autoimmune diseases refer to any condition in which an inappropriate T cell response is a component of the disease. This includes both diseases directly mediated by T cells, and also diseases in which an inappropriate T cell response contributes to the production of abnormal antibodies.
Numerous diseases are believed to result from autoimmune mechanisms. Prominent among these are rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, Type I diabetes, myasthenia gravis and pemphigus vulgaris. Autoimmune diseases affect millions of individuals world-wide and the cost of these diseases, in terms of actual treatment expenditures and lost productivity, is measured in billions of dollars annually.
Adjuvant arthritis (AA) is an experimental autoimmune disease that models several features of human rheumatoid arthritis (1). AA is induced in Lewis rats by immunization with heat killed Mycobacterium tuberculosis (Mt) suspended in Incomplete Freund's Adjuvant (IFA) (1). T-cell reactivity against the mycobacterial 65 kDa heat shock protein (HSP65) is involved in the progression of AA. HSP65-specific T-cells directed against an epitope formed by aa 180-188 (2) cross-react with a self-antigen present in cartilage (3) and can adoptively transfer AA (4, 5). However, vaccination with HSP65 or HSP65-peptides can also prevent the development of AA (6-11). The regulatory properties of HSP65 in AA are thought to involve the activation of T-cells cross-reactive with the endogenous 60 kDa heat shock protein (HSP60) (12). This hypothesis is supported by the finding that immunization with a recombinant vaccinia virus encoding human HSP60 (about 95% homologous to rat HSP60) prevents (13) or treats (14) AA. The inventor of the present invention have recently reported that DNA vaccination with human HSP60 prevents AA (15). Protection from AA was associated with the activation of T-cells responding to HSP60 (15). The human hsp60 molecule was formerly designated HSP65, but is now designated HSP60 in view of more accurate molecular weight information; by either designation, the protein is the same.
A preferable method for treating autoimmune diseases includes modulating the immune system of a patient to assist the patient's natural defense mechanisms. Traditional reagents and methods used to attempt to regulate an immune response in a patient also result in unwanted side effects and have limited effectiveness. For example, immunosuppressive reagents (e.g., cyclosporin A, azathioprine, and prednisone) used to treat patients with autoimmune diseases also suppress the patient's entire immune response, thereby increasing the risk of infection. In addition, immunopharmacological reagents used to treat cancer (e.g., interleukins) are short-lived in the circulation of a patient and are ineffective except in large doses. Due to the medical importance of immune regulation and the inadequacies of existing immunopharmacological reagents, reagents and methods to regulate specific parts of the immune system have been the subject of study for many years.
EP 262710 of Cohen et al. discloses the use of HSP65, or fragments thereof for the preparation of compositions for the alleviation, treatment and diagnosis of autoimmune diseases, especially arthritic conditions. EP 322990 of Cohen et al. discloses that a polypeptide having amino acid sequence 172-192 of HSP65 is capable of inducing resistance to auto-immune arthritis and similar auto-immune diseases. WO 92/04049 of Boog et al. discloses peptides derived from Mycobacterium tuberculosis protein HSP-65 containing at least 7 amino acid residues and inhibits antigen recognition by T lymphocytes in treatment of arthritis and organ rejection.
WO 01/57056 of Karin discloses a method of treating rheumatoid arthritis. The method comprising the step of expressing within the individual at least an immunologically recognizable portion of a cytokine from an exogenous polynucleotide encoding at least a portion of the cytokine, wherein a level of expression of the at least a portion of the cytokine is sufficient to induce the formation of anti-cytokine immunoglobulins which serve for neutralizing or ameliorating the activity of a respective and/or cross reactive endogenous cytokine, to thereby treat rheumatoid arthritis. U.S. Pat. No. 6,316,420 to Karin and coworkers further discloses DNA cytokine vaccines and use of same for protective immunity against multiple sclerosis.
WO 02/16549 of Cohen et al., assigned to the assignee of the present invention, relates to DNA vaccines useful for the prevention and treatment of ongoing autoimmune diseases. The compositions and methods of the invention feature the CpG oligonucleotide, preferably in a motif flanked by two 5′ purines and two 3′ pyrimidines. The vaccines optionally further comprise DNA encoding a peptide or a polypeptide selected from the group consisting of Hsp60, p277 or p277 variants. That disclosure is directed to methods and compositions for the ameliorative treatment of ongoing autoimmune disease in general and Insulin Dependent Diabetes Mellitus (IDDM) in particular.
U.S. Pat. No. 5,993,803 discloses that when HSP60, or peptides and analogs thereof, are administered in a recipient subject before transplantation of an organ or tissue, autoimmunity to HSP60 is down-regulated, resulting in the prevention or suppression of graft rejection of the transplanted organ or tissue.
WO 00/27870 of Naparstek and colleagues discloses a series of related peptides derived from heat shock proteins HSP65 and HSP60, their sequences, antibodies, and use as vaccines for conferring immunity against autoimmune and/or inflammatory disorders such as arthritis. These peptides are intended by the inventors to represent the shortest sequence or epitope that is involved in protection of susceptible rat strains against adjuvant induced arthritis. These sequences further disclose what the inventors identify as the common “protective motif”.
There exists a long-felt need for an effective means of curing or ameliorating T cell mediated inflammatory autoimmune diseases. None of the background art discloses DNA vaccines encoding heat shock proteins for treating T cell mediated inflammatory autoimmune diseases. Such a treatment should ideally control the inappropriate T cell response, rather than merely reducing the symptoms.